The impact of distributed generation (DG) on losses is of great interest in the smart grid research area. This paper analyses how DG locations, automatic voltage controls, generator types, and the operation modes of DGs impact the losses of distribution system. The topology of the grid is selected from the practical distribution network in Xiamen, which is one of the four pilot smart distribution grid cities in China. Shapley Value method is used to identify each DG's individual impact on these losses. Results show that the losses are reduced most significantly when DGs operate at the constant current mode and voltage control mode; followed by the power factor control mode. The induction machine bus could increase the losses. At last, according to the Shapley Values of the DGs, the individual impacts of DGs on losses are location-dependent. The method proposed in this paper has been employed in Xiamen smart grid.